Explosive compositions containing metallic fuel particles and method of preparation thereof

ABSTRACT

An explosive blasting composition of the gel or slurry type which retains its sensitivity to detonation after being agitated or worked and method of making such composition are provided wherein a small amount of collector is added to the composition comprised of a stable dispersion of a metallic sensitizer and/or fuel particle throughout a thickened solution or fluid phase containing at least one inorganic oxidizer salt. The collector remains in solution throughout the fluid phase of the composition.

United States Patent [191 Cook et al.

[54] EXPLOSIVE COMPOSITIONS CONTAINING METALLIC FUEL PARTICLES ANDMETHOD OF PREPARATION THEREOF [75] inventors: Melvin A. Cook, Salt LakeCity;

Mark J. I-lagmann, Summit Park, both of Utah [73] Assignee: IrecoChemicals, Salt Lake City,

Utah

[22] Filed: Feb. 21, 1974 [21] Appl. No.: 444,691

[52] US. Cl. 149/44; 149/41; 149/43; 149/61; 149/46; 149/60 [51] Int.Cl. C0613 33/02 [58] Field of Search 149/44, 41, 43, 46, 60, 149/61 [56]References Cited UNITED STATES PATENTS 3,711,345 l/l973 Tomic 149/44 XDec. 16, 1975 Tomic 149/44 X Tomic 149/44 X 57 1 ABSTRACT An explosiveblasting composition of the gel or slurry type which retains itssensitivity to detonation after being agitated or worked and method ofmaking such composition are provided wherein a small amount of collectoris added to the composition comprised of a stable dispersion of ametallic sensitizer and/or fuel particle throughout a thickened solutionor fluid phase containing at least one inorganic oxidizer salt. Thecollector remains in solution throughout the fluid phase of thecomposition.

12 Claims, No Drawings EXPLOSIVE COMPOSITIONS CONTAINING METALLIC FUELPARTICLES AND METHOD OF PREPARATION THEREOF The present inventionrelates to method of obtaining explosive blasting compositions of thegel or slurry type which retain their sensitivity to detonation afterbeing agitated or worked, and to the resulting explosive compositions.Particularly, it concerns the addition of a small amount of a collectorto an explosive blasting composition comprised of a stable dispersion ofmetallic sensitizer and/or fuel particles throughout a thickenedsolution or fluid phase containing at least one inorganic oxidizer salt.The collector, which is in solution throughout the fluid phase, preventswetting of the surface of the metallic particles by the solution.Prevention of wetting allows explosive compositions to retain theirsensitivity with working as will be more fully explained below.

The use of metallic, notably aluminum, particles in explosivecompositions or blasting agents of the viscous liquid gel or slurry typecontaining a thickened solution of at least one inorganic oxidizer saltand solid and/or liquid fuel has been common throughout the past oryears with the advent of commonly termed slurry explosives." US. Pat.No. 3,297,502 discloses slurry explosives or aqueous blasting agentscomprising water and inorganic oxidizer salts and containing metallicfuel such as aluminum particles having a preformed coating. The aluminumparticles disclosed in this patent function as fuel and have a preformedcoating composed of a liquid oil and a monocarboxylic aliphatic acid.The coating is employed to prevent an aluminum-water reaction whichevolves gas and liberates heat and thus can render an explosivedangerous for storage and handling.

In addition to preventing unwanted reaction of the metal with solution,coating metallic fuel particles prior to their incorporation into anaqueous solution of an explosive composition has also been found toprovide other advantageous results. US. Pat. No. 3,249,474 discloses theuse of aluminum particles having a preformed coating such as stearicacid that renders the aluminum surface lyophobic and thus repellant tothe liquid component of the explosive composition. The coatingsdisclosed in US. Pat No. 3,249,474 are similar to those disclosed in US.Pat. No. 3,297,502. US. Pat. No. 3,249,474 discloses a method ofregulating density and sensitivity of aqueous explosive blastingcompositions whereby such coated fuel is used with an aqueous solutioncontaining at least one dissolved inorganic oxidizer salt. As thispatent describes, it was found that the incorporation of a coatedlyophobic metallic fuel in this manner, coupled with mechanical orchemical aeration or gassing, results in the inclusion of air or gasbubbles which adhere to the surface of the metal particles therebyforming an interface between the metal surface and the aqueous solvent.This adherence of included gas bubbles lowers the bulk density of thecomposition and provides for significantly enhanced sensitivity incomparison to similar compositions not containing lyophobic, coated,metallic fuel.

Apparently, and as suggested in US. Pat. No. 3,249,474, the inclusion ofgas bubbles and their adherence to the surfaces of lyophobic metallicparticles in explosive compositions creates numerous, small voids or gaspockets which are compressible upon initiation or detonation of thecomposition. When a detonation initiation shock wave caused by aninitiator such as a blasting cap or booster travels through such acomposition, apparently the resulting localized and extremely highpressure of the wave compresses these numerous gas pockets causing thegas entrapped therein to obtain an extremely high temperature. Such hotspots" thus created can be sufficient in number and are high enough intemperature, owing to essentially adiabatic compression, to initiaterapid combustion or chemical reaction of the adjacent reactive material,i.e., oxidizer salt in solution and aluminum particles. When asufficient number of such hot spots are simultaneously created, and dueto the ability of a continuous fluid phase to transmit the detonationinitiation shock wave at high velocity, a powerful explosion ensues.This loosely termed hot spot theory is an explanation of the significantsensitizing effect that a small amount of very fine, coated lyophobicaluminum particles having a relatively high surface area (for increasedentrapment of gas bubbles in addition to kindling effect) have beenfound to have in a fluid-phase-based explosive blasting composition.Empirical data coupled with direct density measurements and visualobservation substantiate that lyophobic, coated metallic fuel particlesvastly increase slurry or viscous liquid explosive compositionsensitivity due to the incorporation of small gas or air bubbles intothe composition which adhere to the surfaces of the particles.

Gas bubbles are therefore preferably dispersed throughout an aqueous orfluid solution phase of a slurry explosive composition and can be formedeither by chemical gassing or mechanical entrainment as is well known inthe art. As indicated above, when metallic fuel particles are admixedinto a liquid oxidizer salt solution exposed to air or gas, particularlyone which has been prethickened by thickeners such as galactomannangums, starches, etc., small gas or air bubbles are entrained orincorporated into the solution phase. Further, such bubbles will bestably held in place in a viscous, prethickened solution. Chemicalgassing agents such as decomposing hydrogen peroxide and alkali salts ornitrous acid, which agents can be present in the solution, comprise anin situ gassing means for explosive compositions. A substantialproportion of bubbles formed either mechanically and/or chemicallyadhere to the surface of dispersed lyophobic metallic particles whichcan be considered somewhat as bubble attachment or collection centers.The smaller the bubble, theoretically, the better it functions as areaction site or hot spot. The present invention relates to explosivecompositions which contain a fine dispersion of air or gas bubbles.

Since composition sensitivity is greatly dependent upon adequatedispersion of the coated metallic particles containing attached gasbubbles throughout the aqueous or fluid phase, it is also greatlydependent upon the maintenance of these gas bubbles in this desiredarrangement. It has been found that prolonged storage of explosivecompositions containing finely dispersed gas bubbles, initially adheringto the surfaces of a coated metallic particle when first formed, has insome instances resulted in a loss of composition sensitivity and in manyinstances without a noticeable change in bulk density. Presumably, thisphenomenon is a result of bubble separation from the metallic surfaceand possible subsequent migration and coalescence into larger, lesssensitizing bubbles. Thus while 3 gas is still contained in thecomposition, the gas bubbles are no longer uniformly small and widelydispersed or in adherence to the metallic surfaces. Proper thickeningand cross-linking of the fluid phase can, in most instances, preventmigration, coalescence and bubble separation to a significant degree.

An ever more deleterious phenomenon concerning loss or lowering ofexplosive composition sensitivity is observed when a onceformedcomposition of the coated, metallic fuel and/or sensitizer type issubsequently subjected to some type of agitation. For example, packagedslurry or aqueous explosive composition is oftentimes compactly loadedinto boreholes by tamping which results in a working or agitation of thecomposition. Furthermore, a once-formed composition may be subjected torepumping, or in other words, pumping after initial formation. Forinstance, a composition may be formulated and loaded into a containerand then subsequently pumped or repumped from the container into aborehole or other receptacle. This repumping constitutes another exampleof working.

Working is observed to result in significant desensitization of acomposition containing fine, coated lyophobic metallic particlesdispersed throughout an aerated or gassified fluid phase havingdissolved therein at least one inorganic oxidizer salt. Apparently, suchworking results in a separation of the gas bubbles from the coatedmetallic surfaces, which results in loss of potential hot spots adjacentto the metallic fuel. In effect, the metallic surface becomes wetted,"i.e., the liquid solution is in direct contact with the metal surfaceand is therefore not separated therefrom by an interfacing air or gasbubble. Therefore, wetting of the metallic surface results in a directloss of explosive sensitivity.

A possible explanation of this wetting phenomenon is that workingresults in a loss of the lyophobic coating (e.g. stearic acid, fattyacids, etc.) perhaps due to friction and consequential rubbing off" ofthe coating. Without this coating, the metallic surface is no longerlyophobic and becomes wetted by the liquid solution which displaces theadhering gas bubbles.

It has now been discovered that loss of sensitivity from working of suchexplosive compositions containing coated metallic fuel and/or sensitizerparticles can be prevented by providing, in solution, a liquid collectorwhich is capable of flotation of metallic particles in a liquidmenstruum. As will be shown in the examples below, a collector insolution results in compositions which after being worked will retaintheir sensitivity to a significantly greater extent than compositionsnot containing such an ingredient.

A possible explanation of the observed effect of the collector onsensitivity, which corresponds to that given for the desensitizationupon working phenomenon described above, is that the collector insolution is free to actively seek out and adhere to exposed metallicsurfaces which have lost their lyophobic coating due to working. Thus,liquid collectors in solution allow self healing" of exposed surfaceswhereas solid or preformed coatings will not self-heal. Thus collectorsallow such surfaces to retain their lyophobic nature thereby affordingtheir retention of adhering, interfacing gas bubbles and thus retentionof sensitivity.

The collector used in the present invention may be similar to thecoatings heretofore described in the above referenced patents. However,the collector can be any substance which will cause the flotation of ametallic, preferably aluminum, particle in the liquid menstrum of theexplosive composition, The only essential requirement of the collectoris that it remain in solution, i.e., be a miscible liquid in theexplosive composition solution at temperatures of working of theexplosive. Liquidity and miscibility are necessary in order that thecollector can actively seek out metallic surfaces as they become exposedand thereby continually prevent their wetting as working continues.Examples of collectors of the present invention which have been found tobe effective in various degrees in preventing loss of sensitivity are asfollows: oleic, caprylic, linoleic and other fatty acids; red, tall andcod liver oils; green soap (vegetable oil-potassium hydroxide soap);Fels-naptha', xanthogen ester; sodium sulfated fatty amide derivatives;anionic sulphonates; and sodium lauryl sulfates,

Some of the above collectors have been used heretofore as coatings forthe metallic particle surfaces in explosive compositions. For instance,U.S. Pat. No. 3,297,502 discussed previously discloses the use of fattyacids including oleic acid as coatings that are particularly effectiveif used in conjunction with a liquid hydrocarbon oil such as fuel oil.As mentioned, this patent describes preforming such coating on the metalprior to the particles introduction into the liquid menstruum. U.S. Pat.No. 3,249,474 discussed previously discloses the use of normally solidfatty acids such as stearic acid, palmitic acid, etc., among others aspreformed lyophobic coatings to render the surfaces of the metalparticles lyophobic. As discussed above, neither of these referencesdisclose a means whereby desensiti zation due to working can beprevented. The present invention distinguishes from the disclosure inthese two patents in that while preformed coated metal is preferablyused in the compositions of the present invention, the compositions alsocontain, in solution and in addition, a collector which acts as an insitu, continuous coater or wetting inhibitor of the metal particles.

Thus the present invention has solved a problem which has been prevalentwith the use of slurry or viscous liquid explosive compositionscontaining metallic fuel and/or sensitizer; that problem being loss ofexplosive sensitivity due to working. It has been discovered that theuse of a collector in the liquid menstruum enables such compositions toretain their sensitivity upon working.

It also has been found in the present invention that the use of afrothing agent or frother as a gas bubble stabilizer in conjunction withthe use of a collector allows for even increased composition sensitivityretention upon working. Frothers which limit bubble size and increasetheir stability afford this added effectiveness, Examples of frothersfound effective for their conjunctive use with collector(s) arepolypropylene glycol methyl ethers such as Dowfroth 250 and lOl2 whichare represented by the following formula:

CH,, (0 C,H,),-oH and which have an average molecular weight range offrom about 200 to about 400. The Dowfroth frothers are further describedin the booklet, Flotation Fundamentals and Mining Chemicals, The DowChemical Company, 1970. Another frother found effective is siliconeresin having a specific gravity at 25C of L06 [.08 and a viscosity at25C of 1,200 2,000 centistokes. This silicone resin is knowncommercially as Union Carbide R-23 and is further described in a ProductInformation Bulletin on Union Carbide R-23, R-230 and RE-23l SiliconeWater Repellants. All of the above three frothers appeared to reducebubble size and increase bubble stability of all bubbles in a thickenedliquid menstruum including those attached to and those separate frommetallic particles. Moreover, all three frothers were found to increaseboth the stability and degree of flotation of aluminum particles in aliquid menstrum when used with a fatty acid collector such as oleicacid. Monocarboxylic acid collectors, i.e., oleic, caprylic, etc., havesome inherent frother characteristics which enhances their use ascollectors.

A procedure for determining the relative effectiveness of a collector inpreventing wetting of metallic particles was devised wherein twosolutions, one containing water and the other containing dissolvedammonium nitrate (AN) were admixed with atomized aluminum particles anda collector and the degree of subsequent flotation of the particles inthe solutions was observed. The atomized aluminum tested did not containa preformed coating. ln this simplified test 200 ml of solution wasplaced in a 300 ml flask and 5 gms of atomized aluminum were added.Thereafter, each collector was added in an experimentally optimum amountwhich was about one-hundredth of the mass of the particles (0.05 gm) forthe collectors tested (although each collector differed slightly).Soaps, however, were found to also be effective at a much lowerconcentration. After addition of the collector, the flask was stopperedand given ten hard vertical shakes. The subsequent degree of flotationof the atomized aluminum was then observed. As a standard referencepoint, oleic acid was found to provide 90% of all aluminum particlesfloated on top of the solution due to adhering gas bubbles and of theparticles fell to the bottom of the flask) in a 50/50 by weight ANIH- Osolution. When a collector was not used, no flotation (0%) was observed.A Hallimond-Ewers flotation cell was also used in similar testing, butit tended to over-rate the effectiveness of the collectors since itwould not distinguish between momentary (an order of a second) andprolonged (an order of several seconds or longer) flotation.

Flotation results are shown in Table I. As is readily apparent fromTable I, green soap was found to be the best collector in AN containingsolutions. Fels-Naptha was equivalent to green soap, but, when tested,it was not compatible with solutions containing calcium nitrate (CN).The fatty acids tested and reported in Table l were liquid at roomtemperatures (oleic, caprylic and linoleic). Other fatty acids withgreater chain length such as capric, lauric, myristic, palmitic andstearic were found to work equally well at temperatures above theirsolidification temperatures even through they are solids at roomtemperature. The degree of flotation was substantially lessened whenthese longer-chained fatty acids were used in solutions havingtemperatures below their solidification temperatures. These latter acidsare therefore applicable for use as collectors in the present inventiononly if the explosive compositions are worked at temperatures abovetheir respective solidification temperatures. Short chain length fattyacids such as caproic, valeric, butyric, isobutyric and propionic causedno noticeable flotation presumably because they are not sufficientlywater repellant. Red oil (crude oleic acid), tall oil and cod liver oilwere found to have flotation characteristics equivalent to oleic acid.

It was also found that the optimum quantity of oleic acid is aboutone-hundredth the mass of the atomized aluminum for maximum flotationand is further roughly proportional to the surface area of the aluminumparticles used. The fraction of flotation obtained as well as itsstability was found to increase with increasing fineness of the atomizedaluminum. The finest atomized aluminum tested had a particle sizedistribution such that 62% was 325 Tyler mesh. [t is possible that toofine of particles would not have sufficient surface for bubble contact;however, such an effect was not observed down to the particle size rangetested.

A series of tests was accomplished to determine the effect of pH onflotation of atomized aluminum in water containing tall oil as thecollector. Maximum flotation was found in the pH range of from 4 to 6but was only slightly diminished over the pH range of from 3 to 7.Dilute nitric acid and ammonium hydroxide or acetic acid and sodiumhydroxide were used for adjusting the pH. All other collectors testedwere found to perform similarly in this pH range of from 3 to 7.

Hydrophilic colloid thickeners such as galactomannan gums, flours,starches, xanthomonas gums produced from the bacteria Xanthomonascampesrris, etc., are commonly used in aqueous slurry explosivecompositions. Such thickeners render the aqueous solution viscousthereby preventing segregation of dispersed solid ingredients such asmetallic fuels and/or sensitizers, undissolved oxidiizer salts.carbonaceous fuels, etc., as well as preventing migration andcoalescence of finely dispersed gas bubbles. Such thickeners alsoprovide water resistance to the compositions to prevent breakdown of thecompositions and leaching of oxidizer salts in the presence of water. Ingeneral, thickeners are almost essential for stability, homogeneity andwater resistance of aqueous gel or slurry type explosive blastingcompositions. For added stability thickeners can be cross-linked bycross-linkers such as metallic ions. Slurry explosive cross-linkers andthickeners are widely used and common in the art.

Thickeners are essential to compositions of the present inventionparticularly for preventing metallic particle segregation and gas bubblemigration. Thus a series of tests was made in which atomized aluminumwas found to have good flotation characteristics in water thickened withsmall quantities (concentrations were just below the values at which theviscosity of the solution would significantly interfere with particulatemobility and thus degree of flotation) of Brazilian tapioca flour, guargum derivative of low molecular weight (Stein-Hall L808) and xanthomonasgum (General Mills XB23) and containing oleic acid as a collector. Othercollectors were found to be similarly compatible with hydrophiliccolloid thickeners.

When the collectors were tested for flotation of atomized aluminum inaqueous ammonium nitrate solutions it was found that a fraction of eachof oleic, caprylic and linoleic acid and red, tall and cod liver oilformed a white insoluble product although good flotation was stillobserved. A similar product was not observed with solutions containingcalcium and sodium nitrates. The white insoluble product is attributedto a reaction between the ammonium radical and the by droxy fatty acidcomponent present as an impurity in the collectors.

Combinations of different collectors and combinations of collectors withother ingredients were found to provide particularly good flotation.Fuel oil did not by itself cause flotation, but. when combined witholeic acid as the collector in solution, flotation was enhanced overthat obtained by oleic acid separately. This same effect was observedwith ethylene glycol. A combination of green soap and oleic acid wasfound to cause better flotation than that obtained by either separately.Higher order combinations such as oleic acid, fuel oil. ethylene glycoland frother were also found to be very effective.

Table ll summarizes test results obtained for slurry or gel typeexplosive blasting compositions using various collector/frothercombinations. All percentages refer to weight percent based on the totalcomposition. The CN refers to Norsk Hyro calcium nitrate which is acommercial grade CN consisting of about 80% CN, about 15% water (aswater of crystallization) and about AN. The thickener was General MillsXB-23, a biopolymer gum produced from the bacteria Xanthonomonascampestris.

The compositions of Table II were prepared by first dissolving theoxidizer salt(s) in an aqueous solution containing water, liquid fuels(if any), thiourea as a nitrate gassing agent accelerator (if used), thethickening agent, a collector or combination of collectors, and frother(if used). Such dissolution was accomplished at a temperature preferablyof about at least C higher than the fudge point or crystallizationtemperature of the solution. Thereafter, the remaining solid ingredientswere added to the thickened solution (i.e., aluminum, gilsonite, groundAN) along with the nitrate gassing agent. The composition wassubsequently mixed to provide a uniform, homogeneous dispersion of solidingredients throughout an aqueous fluid phase.

The detonation results of Table II indicate the minimum booster requiredto detonate a 2-inch diameter explosive charge at 5C. The symbol F"stands for failure of the charge to detonate and Det" stands foreffective charge detonation. The No." 5, 6, etc., stands for the size ofa standard commercial blasting cap used as the booster with the largerthe number corresponding to the greater the cap boostering power. Anumber such as 5" followed by a g" represents that the charge would notdetonate with a regular cap and thus stands for the amount of grams of apentolite booster required for detonation. Minimum booster required fordetonation is a direct measure of an explosive compositions relativesensitivity. The smaller the booster. the more sensitive thecomposition.

As shown in the table, the compositions were tested for relativesensitivity both before and after working. Working was accomplished byrepumping an explosive composition through a Model H724 Viking pump at arate of 80 pounds per minute. A 40-pound sample of slurry was used andthus was cycled through the pump two times per minute. A comparison ofthe detonation results of mixes A. B and C shows that oleic acid as acollector has little effect on sensitivity of a composition which hasnot been worked or repumped, but greatly enhances the sensitivity of acomposition which has been worked relative to a composition notcontaining the collector. A comparison of the results of mixes E and Fshows that when a frother is used with an oleic acid collector, thesensitivity of the composition after repumping or working is greaterthan if the frother is not used. A comparison of the results of mixes Gand H shows that when fuel oil is used with oleic acid the sensitivityof the composition after working is greater than if the fuel oil is not,used. In fact. the results for mixes H and l surprisingly, show thatsensitivity is even increased upon working. Fiyrthermore, it is alsogreatly significant, as evident from the results of mixes H and I, thataqueous explosive composition sensitivity may be obtained at higher thannonnal slurry densities due to the control of bubble size and locationby the use of frothers and collectors.

In example I, a soap was used as a collector which increased thecompositions sensitivity upon working. Such result is significant sincesoaps have been generally regarded as desensitizing agents for slurriessensitized by paint grade aluminum.

All of the results shown in Table ll are consistent with the resultsshown in Table l as well as the results of various flotation testsdescribed previously.

The explosive compositions of the present invention are designed toretain their sensitivity after being subjected to working. They are alsocapable of stability over prolonged storage due in some respect to theability of a collector to maintain adherence of fine gas bubbles to thesurfaces of metallic fuels and/or sensitizers.

While the explosive compositions of the invention may, if desired, beused, i.e., detonated, immediately after being placed into a borehole,they also remain stable and this may be detonated even afterencountering water in the borehole and/or being allowed to re main inthe borehole for many days.

In addition to being used unpackaged, e.g., in large diameter boreholeblasting operations, the compositions may also be packaged in anysuitable container, for example, plastic bags or cardboard tubes, andthereafter detonated in either vertical or horizontal boreholes or anyother desired location.

While the present invention has been described with reference to certainillustrative examples and preferred embodiments, various modificationswill be apparent to those skilled in the art and any such modificationsare intended to be within the scope of the invention as set forth in theappended claims.

Table l Flotation of Atomized Aluminum With Various Collectors [Listedby descriptive name [brand chemical or both] and commercial manufacturerin some instances) Flotation Rating Aqueous Solution Containing AN Water[did-- Table l-continued Flotation of Atomized Aluminum With VariousCollectors (Listed by descriptive name lbrand. chemical or bothl andcommercial manufacturer in some instances) Flotation Rating* AqueousSolution Water Containing AN Cresylic acid 2 S A ralmg of l indicatesflotation superior to that obtained with commercially 5. A methodaccording to claim 1 wherein the collector is a soap.

6. A method according to claim 2 wherein the frother is selected fromthe group which consists of polypropylene glycol methyl ether andsilicone resin.

7. A method according to claim 1 wherein the metallic particles arealuminum.

8. In an explosive composition comprising a thickened solution phase ofat least one oxidizing salt and coated (stearic acid) atomized aluminumand a rating of 5 indicates no flotation. mfitanic part cles as fue ansensitizer dispersed throughout the solution phase the improvement com-Table ll AN 27. l SN H O Thiourea Thickener No.6 Det No.5 F. No.5 F.No.5 F.

1.23 35g Det 1.08 l60g F.

1.19 35g Det g F. 5g F.

l .20 5g Det 1.16 5g Det No.8 F. No.3 F.

Mix F used Union Carbide R-23. mixes G and H used Dow DFF-4082.

What is claimed is:

l. A method for preventing the loss of sensitivity of a gas-containingblasting composition upon being worked which composition comprises acontinuous thickened solution phase having dissolved therein at leastone inorganic oxidizer salt and metallic particles as fuel and/orsensitizer dispersed throughout the solution phase which method includesincorporating into the solution phase a small amount of a miscible,liquid collector, which is capable of causing floatation of the metallicparticles in the solution phase when such phase is not thickened andwhich retains its liquidity and miscibility at intended temperatures ofworking.

2. A method according to claim 1 which includes the additional step ofadding a frother to the fluid phase to stabilize and control bubblesize.

3. A method according to claim 1 wherein the collector is a fatty acid.

4. A method according to claim 3 wherein the fatty acid is oleic acid.

No.6 Det No.6 Det 5g Det No.8 F.

1.45 l60g F.

1.45 l60g Det 1.22 L23 No.6 Det No.6 Del No.5 F. No.5 F. g F.

1.34 No.8 Det 1.35 No.8 Det 1.37 lg F.

l .20 5g Det No.8 F.

[.36 353 Det L40 35g Det 1.17 loOg F.

LlU

prising, in the solution phase, a small amount of a miscible, liquidcollector. which is capable of causing flotation of the metallicparticles in the solution phase when such solution phase is notthickened and which retains its liquidity and miscibility at intendedtemperatures of working, to prevent the metallic particles from becomingwetted upon working thereby causing the composition to lose itssensitivity.

9. A composition according to claim 8 wherein the collector is a fattyacid.

10. A composition according to claim 9 wherein the fatty acid is oleicacid.

11. A composition according to claim 8 containing, in addition. a smallamount of a frother to stabilize and control bubble size.

12. A composition according to claim 11 wherein the frother is selectedfrom the group which consists of polypropylene glycol methyl ether andsilicone resin.

1. A METHOD FOR PREVENTING THE LOSS OF SENSITIVITY OF A GASCONTAININGBLASTING COMPOSITION UPON BEING WORKED WHICH COMPOSITION COMPRISES ACONTINUOUS THICKENED SOLUTION PHASE HAVING DISSOLVED THEREIN AT LEASTONE INORGANIC OXIDIZER SALT AND METALLIC PARTICLES AS FUEL AND/ORSENSITIZER DISPERSED THROUGHOUT THE SOLUTION PHASE WHICH METHOD INCLUDESINCORPORATING INTO THE SOLUTION PHASE A SMALL AMOUNT OF A MISCIBLE,LIQUID COLLECTOR, WHICH IS CAPABLE OF CAUSING FLOATATION OF THE METALLICPARTICLES IN THE SOLUTION PHASE WHEN SUCH PHASE IS NOT THICKENED ANDWHICH EETAINS ITS LIQUIDITY AND MISCIBILITY AT INTENDED TEMPERATURES OFWORKING.
 2. A method according to claim 1 which includes the additionalstep of adding a frother to the fluid phase to stabilize and controlbubble size.
 3. A method according to claim 1 wherein the collector is afatty acid.
 4. A method according to claim 3 wherein the fatty acid isoleic acid.
 5. A method according to claim 1 wherein the collector is asoap.
 6. A method according to claim 2 wherein the frother is selectedfrom the group which consists of polypropylene glycol methyl ether andsilicone resin.
 7. A method according to claim 1 wherein the metallicparticles are aluminum.
 8. IN AN EXPLOSIVE COMPOSITION COMPRISING ATHICKNEED SOLUTION PHASE OF AT LEAST ONE OXIDIZING SALT AND METALLICPARTICLES AS FUEL AND/OR SENSITIZER DISPERSED THROUGHOUT THE SOLUTIONPHASE THE IMPROVEMENT COMPRISING, IN THE SOLUTION PHASE, A SMALL AMOUNTOF A MISCIBLE,LIQUID COLLECTOR, WHICH IS CAPABLE OF CAUSING FLOTATION OFTHE METALLIC PARTICLES IN THE SOLUTION PHASE WHEN SUCH SOLUTION PHASE ISNOT THICKENED AND WHICH RETAINS ITS LIQUIDITY AND MISCIBILITY AATINTENDED TEMPERATURES OF WORKING, TO PREVENT THE METALLIC PARTICLES FROMBECOMING WETTED UPON WORKING THEREBY CAUSING THE COMPOSITION TO LOSE ITSSENSITIVITY.
 9. A composition according to claim 8 wherein the collectoris a fatty acid.
 10. A composition according to claim 9 wherein thefatty acid is oleic acid.
 11. A composition according to claim 8containing, in addition, a small amount of a frother to stabilize andcontrol bubble size.
 12. A composition according to claim 11 wherein thefrother is selected from the group which consists of polypropyleneglycol methyl ether and silicone resin.